Retell
OpenAI says Retell uses GPT-6 Astra to power 100M monthly calls
OpenAI says Retell uses GPT-6 Astra for voice agents, with Codex helping it reach a $1.6M annual revenue run rate per employee.
Retell
AI voice agent pricing splits between flat rates and metered stacks
Public AI voice agent prices on Oct. 20, 2026 ranged from flat all-in rates to layered per-minute and token-based billing, with carrier fees often extra.
Retell
Vapi, LiveKit, Retell and Pipecat differ by orchestration layer
AssemblyAI’s comparison says the four voice-agent stacks sit at different layers, with trade-offs in control, transport and STT integration.